Shoes with improved comfort are sought after by consumers, and thus comfort is a goal of shoe suppliers. Comfort is provided in three basic ways, materials of manufacture, shoe shape and cushioning. In addition to comfort, shoes worn at work sites are constructed to provide an extra margin of safety. Some safety features include hard safety toes and slip resistance. Slip resistance is an important feature in shoes worn at certain work sites such as restaurants where liquids such as oil and water are frequently on the floors in areas where workers walk and stand. In addition to these functional features, style can also be important, particularly in areas where the public visits. Shoe choice by an individual takes both comfort and function into consideration as well as style. One popular style is the so-called clog which has a large toe box and is of a slip on style. In contrast to athletic shoes, the clog type shoe is devoid of laces, straps, zippers or the like which secure the shoe more tightly to the user's foot. Clog shoes are also devoid of ankle support. Both the laces and the ankle support provide stability to the shoe with the sacrifice of comfort. Athletic shoes are often worn for short periods of time and are generally impractical for use in a job setting where they would need to be worn for as long as twelve hours at a time. Clogs, in contrast, are not cinched to the user's feet and thus provide more comfort to persons wearing the shoes for long periods. However, as stated earlier, clogs do not provide the stability provided by athletic shoes. Another shortcoming to a clog type shoe relates to the heel. Heels cause the heel of the shoe and thus the heel of the foot to strike the ground prior to the forefoot. Heel strikes often result in a potentially injurious impact force at the beginning of a stride cycle that is not seen when the forefoot strikes the ground first. This means that heel cushioning must be of particular concern when designing a shoe for heel strikes.
Cushioning can be provided by the insole, midsole and outsole with suitable materials of construction. Although soft soles provide comfort, they tend to be very flexible. Many of these components are made of a cellular or foam material. In addition, air cushions have been used in the heel area of the shoe particularly to reduce impact forces. The cushioning is used to reduce impact on the shoe user during use of the shoe, particularly during fast walking and running where the heel of the user first impacts the underlying surface. One problem with air cushions is that movement of entrapped air inside the cushion in one area causes other areas of the cushion to accommodate that movement, e.g., if one area is compressed, another area expands in a flexible fluid filled cushion. This cushion deformation is commonly referred to as transfer of motion. This movement of fluid is particularly present in large single chamber cushions. One means of reducing this reactive cushion deformation is to provide columns extending between and connected to the upper and lower surfaces of the cushion to restrict movement of the top surface of the air cushion with respect to the bottom surface. Transfer of motion can result in a feeling of instability if the deformation of the cushion is along the side edges of the cushion.
Another solution to the cushion deformation is the use of a plurality of cushions in the heel area that will limit fluid movement and hence transmission of deformation, keeping deformation more localized. This however is reputed to limit the cushion effect and increases the cost and complexity of a shoe. There is thus a tradeoff between cushion stability and the cushioning effect.
Another problem with shoes of comfort is their flexibility both laterally and longitudinally. Longitudinal flexure (bending in an area transverse to the longitudinal axis of the shoe) can be somewhat controlled by use of a shank in the heel area and midfoot area of the shoe. Flexure can also be limited by the use of thick, heavy and rigid soles instead of soft flexible soles, but at the cost of comfort to the wearer.
There is thus a need for an improved shoe construction to overcome the problems attendant with the use of fluid cushioned shoes using lightweight flexible materials of construction. The shoe construction should provide stability to clog type shoes having particularly thick heel areas with air cushions therein.